Method and apparatus for providing inductive coupling and decoupling of high-frequency, high-bandwidth data signals directly on and off of a high voltage power line

ABSTRACT

The present invention is drawn to an electrically “closed” method and apparatus for transmitting and receiving data signals over a high voltage power line. Inductive coupling is employed for coupling and decoupling the data signal directly on to and off of a single power line wire. An exemplary device includes a high frequency inductive coupling toroid for data signals, a second (50-60Hz) inductive coupling toroid for providing power, signal conditioning electronics for the receive and transmit signal, a fiber optics interface for electrical isolation purposes, and a weather-proof enclosure. In a preferred embodiment, the toroids are hinged for ease of installation on a power line. A pair of such couplings on either side of a fiber-optic isolator can be used to bridge transformers.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119(e) fromprovisional application no. 60/268,578, filed Feb. 14, 2001. The60/268,578 provisional application is incorporated by reference herein,in its entirety, for all purposes.

FIELD OF THE INVENTION

The present invention is concerned with the field of transmitting andreceiving high frequency, high bandwidth signals safely and efficientlyover power lines. An exemplary system comprises a power line coupler ofthe present invention, a fiber optic isolator and a communicationsinterface to various media. More specifically, the present invention isdrawn to a method and apparatus for coupling to a high voltage powerline for transmitting and receiving high frequency, high bandwidthsignals.

BACKGROUND

With well-established power distribution systems (PDSs) already in placethroughout much of the world, an efficient power line communicationsystem (PLCS) could provide more users with high-speedtelecommunications access with the minimum investment of “add-on”devices.

The infrastructure for providing broadband Internet access is presentlyinsufficient to meet demand. A power distribution system (PDS), however,could be an ideal vehicle for carrying communications signals in orderto meet this demand.

Development of a power line communication system (PLCS) would thereforeprovide more users with high-speed telecommunications access. Since thePDS is already built, the time required to implement a PLCS would beminimal.

Of course, there are a series of problems to be overcome before a PDScan be used as an efficient, high-speed power line communicationsmedium. The following issues, while not exhaustive, are representativeconsiderations of what such a system would require in order to use anexisting PDS to transport communication data: a sufficient signal tonoise ratio; non-disruptive installation of the “add on” device; safetymeans such that users and circuitry are protected and isolated fromstray current; a signal carrier with a frequency sufficient to supporthigh data transfer rate (e.g. 10Mbps); means for the data signal tobypass a distribution transformer without loss; bidirectional datatransmission; coupling devices that do not interfere with data signalhandling; an independent power source for electronic conditioningcircuitry at power line interfaces; a power line interface that isimpervious to extreme environmental conditions; and means for the datato be readily routed to intended locations without loss.

Given the advantages of being able to use the existing PDS forhiqh-speed data communication, an effective method is required to coupleand decouple the signals onto and off of a high or medium voltage powerline. The coupling and decoupling of the data signal must be at a levelsufficient to maintain an adequate signal to noise ratio in order todiscern between the data signal and noise or interference on the line.For any method developed, a significant challenge lies in being able tomitigate the adverse effects of the high voltage 50-60Hz power signalmight have on the communications signal.

Whyte, et al. in U.S. Pat. No. 4,142,178 observe: “The use of thedistribution network conductors for the transmission of carriercommunication signals presents many problems not encountered in highvoltage transmission line communication systems. Some of these problemsinclude the poor high frequency impedance characteristics and the highlevel of electrical noise present on the distribution network conductorswhich, along with the plurality of distribution transformers and powerfactor correction capacitors attached to the distribution network,rapidly attenuate the communication signals.”

Whyte teaches using a direct circuitry from a line coupler to a remotedata terminal thus bypassing the PDS transformer, which is the primarysource of data attenuation. The main use for the transmission ofcommunication signals addressed by Whyte was to perform distributionfunctions such as automatic reading of utility meters and selective loadcontrol. Those functions are still desirable, but the function of highspeed, high bandwidth communication transmission preclude directconnection from a transformer to remote data terminals economically.

Use of a low voltage power distribution system as a data communicationscarrier within a premises is well known. Abraham, U.S. Pat. No.6,014,386 teaches a communications network within a building using theAC wiring as the infrastructure of the network. Different types ofappliances using digital signals may be included within the network. TheAbraham patent uses an impedance matching scheme to direct a specificsignal to a specific location. Couplers at a control location haveunique impedances that are matched by corresponding couplers elsewherewithin the building. Thus, specific signals will be de-coupled based animpedance match. Abraham also teaches the use of dielectric inductors incircuit with capacitors to tune the impedance characteristics ofcouplers.

In a similar manner, Abraham in U.S. Pat. No. 5,625,863 teaches thedistribution of multiple video signals distributed within a buildingusing the building's AC wiring as the distribution system. Uniqueimpedance settings direct the signals to unique locations. Abraham inU.S. Pat. No. 5,818,127 describes a distribution system for FM signalswithin a building by use of the building's AC wiring.

Abraham in U.S. Pat. No. 5,717,685 describes the coupling of data signalon and off a building's AC wiring infrastructure. His invention usescapacitive circuits in serial connection. The circuitry also includesair-core transformers. This arrangement allows impedance tuning of thespecific couplers. While Abraham claims a system with a fiber opticsource for an input signal in his 6,014,386 patent, there is nodescription as to the use of fiber optic isolators.

Abraham also states that the utility firm may use the communicationssystem to communicate utility meter information over the PDS.

Methods for avoidance of distribution transformers are well known.Perkins in a series of patents including U.S. Pat. No. 4,473,816 teachesa communications signal bypassing a multi-phase power transformer wherethe signal uses the PDS as a carrier. The signal is bi-directional anduses conductive material to affect the bypass. The invention usesmultiple capacitors in parallel to neutralize the coupling impedance.Further, the winding ratio, R, between the primary and secondarywindings ratio is maintained in the signal frequency across the signalbypass. Signal carrier frequency is in the 3-10KHz range. Similarly,Perkins in U.S. Pat. No. 4,473,817 teaches a communications signalbypassing a single-phase power transformer.

Kennon, U.S. Pat. No. 4,644,321 uses a non-intrusive coupler to capturethe data signal. Kennon teaches the use of a toroid having amultiplicity of turns of a conductor that is in circuit with anamplifier and receiver. The toroid core is non-conductive. The signalthus inductively de-coupled is amplified and used for a load managementand filed configuration utility terminal. The system requires a batteryfor circuitry management.

Brown, U.S. Pat. No. 5,949,327 teaches the use of transformer bypass bycoupling using capacitors connected to the primary and secondaryterminals of the step transformer. Brown recognizes the need formultiple couplings at different points within the EDN (ElectricalDistribution Network or, as referred to in the present description asPDS). Brown also teaches that the communication system use a highfrequency signal carrier technique such as CDMA.

Moore, U.S. Pat. No. 5,210,519, describes a communication system thatcouples data signal from a transmission source using an inductor andde-couples the data at the receiver. This methodology is applied in aclosed network and requires selective de-coupling as opposed to routingof the signal. Further, Moore teaches the use of a second transformerfor reversing any inductor core saturation that may have occurred in thedata de-coupling. This method requires time division of the data couplerbetween data coupling and saturation neutralization.

Dzung, European Patent Application EP948143, describes a high voltagepower line communication system that combines multiple source datasignals, couples the combined signal onto multiple power lines usingcapacitive coupling and de-couples and demodulates the signals,separating and converting the signals back to the original form at thereceiver.

Power lines can be located in areas with extreme environmentalconditions. Thus, the mechanical design must ensure proper operationwhen exposed to these extreme conditions and also maintain the requiredlevel of safety. Furthermore, any methods developed should be designedso as to have minimal impact to service of customers duringinstallation.

Public safety is an absolute requirement. Any system using the PDS mustisolate the end user (and public in general) from exposure to electriccurrent. The PDS steps medium and high voltage power down to low voltagepower (approximately in the 100-240 volt range) using transformers.Transformers are designed to filter out and ground high frequencysignals as a safety precaution. Since a high frequency signal carrier isthe ideal medium for high bandwidth data transfer, a communications datadelivery system needs to circumvent the transformer filtration processwhile preserving safety protection.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a power line couplerdevice for use with a power line communication system (PLCS).

It is another object of the present invention to provide a power linecoupler device for use with a high frequency signal carrier sufficientto support high data transfer rates.

It is still another object of the present invention to provide a powerline coupler device that operates under the various line voltages withinthe PDS.

It is yet another object of the present invention to provide a powerline coupler device that enables electrical current isolation.

It is still a further object of the present invention to preserve signalto noise ratio for the communications signal.

It is yet a further object of the present invention to preserve signalto noise ratio for the communications signal bi-directionally.

It is another object of the present invention to provide inductivesignal coupling in a PDS.

It is a further object of the present invention to provide inductivesignal coupling in a PDS where the couplers core remains unsaturated.

It is a further object of the present invention to provide a power linecoupler device that is non-intrusive.

It is still a further object of the present invention to provide a powerline coupler device that inductively draws operating power from thepower line.

It is a further object of the present invention to provide a power linecoupler device that is self-contained.

It is a further object of the present invention to provide a power linecoupler device that is self-contained and is nearly impervious toenvironmental conditions.

It is another object of the present invention to provide a power linecoupler device that uses a toroid inductor to inductively couple andde-couple signals to and from a power line.

It is yet another object of the present invention to provide a powerline coupler device that provides an electronic-to-light transducer tointerface with a light conducting isolator.

It is still another object of the present invention to provide anon-intrusive power line coupler device with a hinged power line couplerfor ease of installation.

The PDS topology can be used to deliver high-speed communications toresidential homes in a cost effective way. Applications for suchcommunication systems include high speed Internet, telephony, videoconferencing and video delivery. This recitation of applications is notmeant to be exhaustive.

The system involves coupling and de-coupling communications data betweena data source and a PDS. High frequency signals allow high bandwidthtransfers (the higher the frequency of the data carrier, the more cyclesper unit time available for data transfer). The signal carrier shouldexhibit high signal to noise characteristics relative to the underlyingsystem of a 50 or 60 Hz PDS. (The US standard is 60 Hz, but mostcountries use a 50 cycle per second power system.)

The data signals are coupled on to and off of the power line with apower line coupler (PLC) device. One embodiment of the present inventionuses an inductive method to couple and de-couple data signals off of thepower line. A toroid with conductive windings is placed around the powerline. This method effectively provides a transformer between the powerline and the PLC device circuitry thus facilitating the transmission andreceiving of the data signal. For the primary side of the transformer,the number of windings and the orientation of the windings around themagnetic toroid is guided by the desire to maximize the flux linkage.

The type of signal used on this channel can be almost any signal used incommunications (CDMA, TDMA, FDM, OFDM to name a few). A wideband signalsuch as CDMA that is relatively flat in the spectral domain is preferredto minimize radiated interference to other systems while delivering highdata rates.

Since communications signals are very high frequency, a step downtransformer would filter a signal coupled on the power line. The systemto which present invention is a component avoids filtering of highfrequency signals by bypassing the transformer with a power line bridge(PLB). The PLB, using a PLC device, de-couples data signals from themedium (MV) or high voltage (HV) line a short distance from atransformer. The PLB interfaces between the power line on the primary ofthe transformer and the low voltage (LV) line on the secondary of thetransformer. (The primary is the side of the transformer where therelatively high voltage enters; the secondary is the side of thetransformer where the stepped down, lower voltage exits thetransformer.)

The PLB is used to prevent the relatively high voltage from passing tothe transformer's secondary side yet allowing the communications signalto pass between the PDS on either side of the transformer. The bypass isaccomplished with the use of an isolator. The PLC device includescircuitry to interface with an isolator. A preferred embodiment of thesystem of which the present invention is a component is to use anoptical medium as an isolator.

The de-coupled signal from the relatively high voltage power line isconverted to light energy (i.e. light signal) by using a transducer andtransmitting the light signal over a non-electrically conductive butlight conductive medium.

A preferred embodiment of the present system uses a fiber optic cable asthe isolator. The isolator is a light pipe that bypasses thetransformer. Fiber optic cable is a dielectric thus insulating the PDSon the secondary transformer side from relatively high voltage.

As described in a companion application by the present inventor,application Ser. No. 09/835,532 filed Apr. 16, 2001, the signal is nextmodulated and demodulated by a first modem. The signal goes through adata router and then a second modem. The router serves the purpose ofmatching data packets with specific messages and destinations. Thesecond modem modulates and demodulates the signal in a form consistentwith transport over a LV power line.

The light signal is converted back to an electronic signal and thencoupled onto the LV power line (LV coupler). In an embodiment of thepresent invention a second isolator is inserted in the system betweenthe second modem and the data router for conversion of the light signalto electrical signal. Additionally the isolator proves an additionallayer of safety because of the dielectric quality of the secondisolator.

The high speed, high frequency signal is then delivered, over the LVpower line to the end user's residence or place of business. A powerline interface device (PLID) serves as the gateway between the enduser's various data appliances and local area network (LAN) and the highspeed data transport.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 discloses the typical electric distribution topology of the priorart.

FIG. 2 illustrates typical electric distribution topology modified forcommunication in accordance with the present invention.

FIG. 3 illustrates a block diagram of the AP in accordance with thepresent invention.

FIG. 4 illustrates a block diagram of the PLB in accordance with thepresent invention.

FIG. 5 illustrates a conceptual diagram of a power line coupling inaccordance with one embodiment of the present invention.

FIG. 6 illustrates a diagram of a self-contained power line coupling inaccordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is a power line coupler device specially suitedfor coupling and de-coupling high frequency, broadband signals carriedover power lines within a power distribution system. The PLC deviceincludes the coupler and circuitry necessary to condition the signal, tohandle bi-directional signal transfer, to enable the use of an isolator,to be self-contained and to be able to provide operational power fromthe power line. The PLC device is part of an overall power linecommunication system (PLCS) which incorporates the present invention andother, companion inventions from the same inventor. The followingdescription is a description of the PLCS in general. The PLC deviceembodiment is included in the system description. The descriptionpertinent to the PLC device should be apparent to one skilled in theart.

Referring to FIG. 1, the typical electric distribution topology of theprior art is illustrated. Medium voltage (MV) half loop power deliverysystem, as illustrated, is common to the U.S. PDS. Many transformers areused. Each transformer services a few homes or small businesses. Manyother countries, such as the European states, use a high voltagedelivery system with many end users serviced from a transformer. Thepresent invention is applicable to either environment.

The power line communication system may be implemented in a high voltageand medium voltage environment (i.e. 1-100 kVAC). For purposes of thisdescription and claims, the high and medium voltage portion of the PDSis described as primary voltage (PV). The low voltage portion of thesystem is described secondary voltage (SV). These terms are arbitrarybut used to improve clarity of the description. Similarly, the side of atransfer where the PV line enters is called the “primary” side. The SVside of the transformer is referred to as the “secondary” side of thetransformer.

A sub-station 10 delivers PV power to a half loop distribution point,pole dip 12. The power is delivered in parallel to multiple transformers20 over a PV power line 14. After the transformer is stepped down to aSV power (in the range of 100 to 240 VAC), several end user premises 26are serviced via a SV power line 24. The step down transformer 20grounds high frequency signals for safety purposes. Since a high datatransfer (high bandwidth) power line communication delivery systemrequires a high frequency signal carrier, an object of the presentinvention is to avoid the removal of the high frequency signal by thetransformer 20. It is noted that the PV power lines 14 may be aboveground or subterranean. The transformers 20 may be aerial mounted on apole or pad mounted on the ground.

FIG. 2 illustrates the typical electric distribution topology as shownin FIG. 1 as modified for communication in accordance with the presentsystem. A point of presence 40 (POP), the gateway for high frequency,high bandwidth data signal, provides communications with digitalproviders. It both sends and receives data to the end user over the PDS.A backhaul link 42 connects the POP 40. Data is manipulated and coupledand de-coupled from the PV power line at an aggregation point 44 (AP). Amore detailed description of the AP follows in the FIG. 3 discussion.

The PDS is viewed as having three channels: PV power line; SV powerline; and the premise's wiring. The first channel has the PV cable) hasthe least amount of noise and least amount of reflections. This channelhas the highest potential bandwidth for communications. This isimportant because it is the channel that concentrates all of thebandwidth from the other channels. The type of signal used on thischannel can be almost any signal used in communications (CDMA, TDMA,FDM, OFDM to name a few). A wideband signal such as CDMA that isrelatively flat in the spectral domain is preferred to minimize radiatedinterference to other systems while delivering high data rates.

The second channel (SV line from the transformer to the premise) andthird channel (premise wiring) have noise present from electricalappliances and reflections due to the “web” of wires. These channelssupport a lower bandwidth than the PV channel and they need a moreintelligent (with more overhead) modulation scheme. There are severalcompanies with chip sets to achieve good communications for local areanetworks (LANs) such as: Adaptive Networks (Newton, Mass.), Inari(Draper, Utah), Intellion (Ocala, Fla.), DS2 (Valencia, Spain) and Itran(Beer-Sheva, Israel). These devices would work well for the SV andpremise channels.

Data signal and power are carried over the PV power line 14 aspreviously stated. A power line bridge 46 (PLB) allows the data signalto bypass the transformer 20 thus avoiding the grounding of the highfrequency data signal. More description of the PLB follows in the FIG. 4description. The data signal after manipulation is delivered to the enduser's premise. The data signal enters premise via the SV wiring. Theend user may have a local area network (LAN) or have individual digitalappliances.

In one embodiment of the present system, the signal is carried throughthe premise's wiring 24 and is available to various digital appliances29, 30, including PC's, by a power line interface device 28 (PLID). ThePLID 28 plugs into a standard electrical socket and allows the digitalappliance to send and receive digital data. An alternative embodiment asdescribed later, uses a communications interface located outside of thepremise and the data signal is directly fed to the premise.

Referring next to FIG. 3, a block diagram of the AP 44 in accordancewith the present invention is illustrated. The AP 44 is the point wheredigital data is coupled and de-coupled to the PV power line.Additionally, the data is processed so that it can be readilycommunicated. Data signal communication to and from POP 40 is providedby the backhaul link 42.

A backhaul interface 50 allows direct communication with POP 40. Thesignal is passed through a high or medium voltage signal modem 52 (PVmodem). An isolator 54 is used to prevent electric current from flowingbetween the PDS and the components leading to the POP 40. The isolator54 is made from dielectric material. The isolator, in a preferredembodiment of the present system, is a fiber optic light pipe. Moredescription of the isolator and its components occurs in the descriptionreferring to FIG. 6.

The isolator 54 bridges between the PV modem 52 and a power line coupler56. The PV modem 52 within the AP 44 conditions the signal fortransmission over the PV power line 14. When data is transmitted by theend user and is de-coupled off of the PV power line, the PV modem 52conditions the signal for transmission back to the POP 40.

In one embodiment of the present system, the power line coupler 56comprises, along with other components, an inductor having a toroid(donut-like) shaped core. The toroid core has permeability qualities toimprove signal to noise ratio. More description of a preferredembodiment for the power line coupler is presented below. The inductorcouples and de-couples a high frequency signal to and from the powerline without invading the power line. Once the data signal has beencoupled to the PV power line, it is transported on the PV power line 14.

Referring to FIG. 4, a block diagram of the PLB in accordance with thepresent system is illustrated. The PLB 46 bypasses the transformer 20linking the data signal between the PV power line and the SV power line.At either end of the PLB 46 is a coupler. A PV coupler 60 couples andde-couples signal with a PV power line 14. A SV coupler 72 couples andde-couples signal with a SV power line 24.

An isolator is present between the PLB end couplers 60,72 and theinterior of the PLB 46. The isolators, a PV isolator 62 and a SVisolator 70, are composed of dielectric material and insulate thebalance of the PLB from potential electrical damage and user injury. Apreferred embodiment of the isolator uses fiber optic material. Theisolator is discussed in more detail below.

A PV modem 64 modulates and de-modulates the signal to and from the PVisolator. The PV modem conditions the high frequency signals fortransmission over the PV power line 14. The SV modem 68 conditions thesignal for communication over a SV power line. In one embodiment of thepresent invention, a data router 66 is between the SV modem 68 and thePV modem 64. The function of the data router 66 is to prioritize andgather packets from all of the devices on SV power line side PV powerline side. The data router 66 provides data packet management of enduser transmission.

The signal (going to the end user) is coupled onto the SV power line bythe SV coupler 72. The SV power line 24 delivers the power service to anend user premise 26. A “web” of wires distributes power and signalwithin the premise. The user draws power on demand by plugging anappliance into a power outlet. In a similar manner, the user may use apower line interface device 28 (PLID) to digitally connect dataappliances, receiving and sending data signals carried by the powerwiring.

A PLID 28 can have a variety of interfaces to the subscriber's equipment30, 32. Some examples are RJ-11 Plain Old Telephone Service (POTS),RS-232, USB, and 10 Base-T. A subscriber can have more than oneinterface device 28 on the same premise wiring.

Referring to FIG. 5, a conceptual diagram of a power line coupler devicein accordance with one embodiment of the present invention isillustrated. The description of the system includes a PLB 46. Theembodiment conceptualized in FIG. 5 replaces the PLB 46 with aself-contained power line coupler device 100, a fiber optic isolator 130and a communications interface 140. Further, the transformer 20 isdepicted as pole mounted. The Communications Interface 140 separatessignal carried over the PV power line 14 into three components: SV powerline 24; wireless link 150; and telephone line 160, although this is notmeant as a limitation.

Referring to FIG. 6, a diagram of a self-contained power line couplerdevice in accordance with one embodiment of the present system isillustrated. The self-contained power line coupler device is packaged ina weatherproof housing 102 to militate against harsh weather andenvironment conditions. The PV power line 14 passes through openings inthe container. A data signal coupler 104 couples and de-couples datasignals transported by the PV power line 14. One embodiment of thepresent invention uses a magnetic toroid shaped inductor. Windings 108are placed around the inductor 104 to facilitate flux linkage of thedata signal. The number of windings and the winding orientation isselected to maximize flux linkage. The permeability of the magnetic coreis chosen for maximum coupling with the high frequency data signal. Corepermeability characteristics prevent low frequency power line signalsaturation of the toroid core. If the inductor coupler 104 becomessaturated with low frequency signal, the coupler would lose its abilityto couple or de-couple high frequency signal. Low frequency, as used inthis description and claims, are frequencies in the range of 1-100 Hz,typically 50-60 Hz.

The toroid 104 has direct electrical connection to the signalconditioning electronics used for transmitting and receiving the datasignal. Transmit and receive circuitry 110 carries data signal to signalconditioning electronic components. As depicted in FIG. 6, the transmitcircuitry 112 and the receive circuitry 114 are in parallel. Anotherembodiment of the present invention uses two data signal couplingtoroids. One coupler is used for receiving and one for transmitting inorder to optimize the flux linkage for the two cases. (FIG. 6, however,depicts only a single signal coupler.)

The design of the transmit side is done to maximize the power of thedrive signal in order to keep the signal to noise ratio of the coupledsignal at least to the level acceptable for the overall communicationssystem. The receive side contains a low noise amplifier designed tohandle the lowest acceptable transmit signal level of the system. At asystem level, the modulation and signaling scheme is done to minimizeinterference between transmit and receive signals.

The signal conditioning circuitry communicates with the fiber opticsinterface via an electronic/light transducer 116. Laser diodes may beused to implement a light transducer. The transducer converts electricalsignal to light signal in the receive circuitry 114. The transducerconverts light signals to electrical signals in the transmit circuitry112. The light signal is transmitted to and from a light pipe 130 (fiberoptic cable). The data signals are communicated back and forth betweenthe power line coupler 100 and the Communications Interface 140 via afiber optic cable 130. The Fiber Optic Isolator breaks any electricalpath between the two devices thus providing safety for the system.

With the power line coupler device being a “closed” system, power forthe electronics must be derived internally. Batteries may be an optionbut replacement would be costly and impractical. In one embodiment ofthe power line coupler device, a power draw toroid 106 is provided. Thepower draw toroid 106 has magnetic characteristics appropriate forcoupling low frequency signals, thus inductively drawing some of thepower off of the power line and providing a power supply 118 for thepower line coupler device.

For additional safety, the power line couple device external shell orhousing 102 is constructed from dielectric, corrosive resistant,weatherproof materials and is designed to significantly reduce anypossible exposure to the high voltage potential present on the powerline. The Fiber Optic Isolator 130 is the only connection between thepower line coupler device 100 and the communications interface 140.Further, the light pipe is encased in the insulated housing 102. Thefirst priority of the housing 102 is to protect from exposure to thehigh voltage potential. It is also designed to ensure proper operationunder extreme environmental conditions. The external shell is assembledusing fasteners including adhesives. The assembled shell is sealed witha dielectric, weatherproof sealant around any seams, fasteners, andpower line and conduit openings. Sealing enhances the weatherproofing.

In another embodiment of the present invention, a “hinged” toroid designallows for easy installation and minimal impact to customer service. Thetoroids, one or two coupling toroids and a power supply toroid, simplysnap around the power line using existing utility tools and techniques.

The communications interface 140 communicates with the power linecoupling device 100 via the fiber optic isolator 130. Received signalsare separated into digital data signals and any other communicationsignal that may be carried by the PV power line. FIG. 5 depicts threetypes of leads from the communications interface: 120/240V power line 24(SV power line); wireless link 150; and telephone link 160. The SV powerline receives current from the transformer 24. The digital data signalis coupled on and off the SV power line 24 within the communicationsinterface.

The description of one embodiment of the present system including a PLB46 for providing a means for converting light signals to coupled digitaldata signals as delivered to a premise over SV power line has been made.The communications interface implements the coupling and de-coupling ofdigital data signal on and off the SV power line in a similar fashion.

A system as disclosed herein is useful to provide data services to theresidential market place at 10 Mbps. This makes an entire new range ofapplications practically available. Each device connected to the PLIDwould (if desired) have an address and would be accessible remotely.Some examples include broadband Internet access, remote utility meterreading, Internet Protocol (IP)-based stereo systems, IP-based videodelivery systems, and IP telephony.

The present system and the present invention have been described interms of preferred embodiments. However, it will be appreciated thatvarious modifications and improvements may be made to the describedembodiments without departing from the scope of the invention.

1. A method for transmitting and receiving high-frequency data signalsover power transmission lines, comprising: coupling and un-couplinghigh-frequency electrical data signals with a first power transmissionline by inductance; conditioning said coupled and un-coupledhigh-frequency electrical data signals; and coupling and un-couplinghigh-frequency electrical data signals to a first end of a fiber-opticcable using a light transducer; and wherein said fiber optic cable isconfigured to isolate power transmission line voltages that may beconducted to said fiber optic cable.
 2. The method of claim 1, furthercomprising providing said inductance by positioning said first powertransmission line inside a toroid shaped core having a plurality ofwindings.
 3. The method of claim 2, further comprising preventing lowfrequency power line signal saturation of said core by forming said corewith a magnetic material of sufficient permeability.
 4. The method ofclaim 2, further comprising forming said core as two portions with ahinge therebetween to ease installation.
 5. The method of claim 1,further comprising inductively providing power for said conditioning andsaid light transducer using a second toroid surrounding said first powertransmission line and including a sufficient number of windings toinductively transfer desired power.
 6. The method of claim 5, furthercomprising forming said second toroid as two portions and joining saidportions together with a hinge.
 7. The method of claim 1, furthercomprising coupling said fiber-optic isolator cable to an interfacedevice for electronic data signal devices.
 8. The method of claim 1,further comprising: coupling and uncoupling light signals from a secondend of said fiber-optic isolator cable using a second light transducerfor high-frequency electrical data signals; conditioning said coupledand un-coupled high-frequency electrical data signals; and coupling andun-coupling high-frequency electrical data signals with a second powertransmission line by inductance.
 9. The method of claim 8, furthercomprising providing a second inductive power source for at least saidsecond light transducer.
 10. The method of claim 1, further comprisingproviding said coupling, un-coupling and conditioning steps within aprotected environment.
 11. A device for transmitting and receivinghigh-frequency data signals over power transmission lines, comprising:an inductor adjacent to a first power transmission line; signalconditioning circuitry electrically connected to said inductor; a lighttransducer electrically connected to said signal conditioning circuitry;a fiber optic cable connected to said light transducer via a first end;wherein said fiber optic cable is configured to isolate powertransmission line voltages that may be conducted to said fiber opticcable: a power source for said signal conditioning circuitry and saidlight transducer.
 12. The device of claim 11, wherein said inductorcomprises a toroid shaped core having a plurality of windings and saidinductor is positioned such that said first power transmission line runsthrough a center of said core.
 13. The device of claim 12, wherein saidcore comprises a magnetic material of sufficient permeability to preventlow frequency power line signal saturation of said core.
 14. The deviceof claim 12, wherein said toroid shaped core comprises two portionsjoined together with a hinge.
 15. The device of claim 11, wherein saidpower source comprises a second toroid surrounding said first powertransmission line and including a sufficient number of windings toinductively transfer desired power.
 16. The device of claim 15, whereinsaid second toroid comprises two portions joined together with a hinge.17. The device of claim 11, further comprising an interface devicecoupled to said fiber-optic cable; said interface device including meansto interface with digital appliances.
 18. The device of claim 11,further comprising: a second light transducer connected to a second endof said fiber optic cable and electrically connected to a second set ofsignal conditioning circuitry; said second set of signal conditioningcircuitry electrically connected to a second inductor; and said secondinductor adjacent to a second power transmission line.
 19. The device ofclaim 11, further comprising a second power source for said second setof signal conditioning circuitry and said second light transducer. 20.The device of claim 11, further comprising a weather-proof enclosure forat least said inductor, said signal conditioning circuitry, and saidlight transducer.